1. Field of the Invention
The present invention relates to an optical film for a display apparatus using electrophoresis and a filter for the display apparatus having the same.
2. Description of the Related Art
Recently, a cathode ray tube (CRT), which has been representative of existing display devices, is being replaced by a flat panel display (FPD), such as a liquid crystal display (LCD), a field emission display (FED), an organic light emitting display (OLED), a plasma display device, or the like. Among them, the plasma display device is in the spotlight because it has an excellent display performance in relation to luminance, a contrast ratio, image retention, a viewing angle, or the like. Hereinafter, the plasma display device will be described for illustrative purposes.
The plasma display device includes a plasma display panel. In the plasma display panel, gas discharge occurs, ultraviolet rays are generated and then a fluorescent material is activated by the ultraviolet rays, whereby visible light is generated. The plasma display device displays an image using the visible light.
However, the plasma display device has drawbacks in that a large amount of electromagnetic waves and near infrared rays are emitted due to its intrinsic characteristics. The electromagnetic waves and near infrared rays emitted from the plasma display device may have a harmful effect to the human body, and cause malfunction of precision appliances such as a remote controller.
Therefore, the plasma display device employs a filter in front of the display panel in order to block electromagnetic waves and near infrared rays. In addition, the filter for the display apparatus is required to have a good performance in relation to color purity, anti-reflection, a contrast ratio, etc. as well as blocking electromagnetic waves and near infrared rays. The filter for the display apparatus satisfying the above requirements is being manufactured.
In order to satisfy those requirements, the filter for the display apparatus is generally made by layering together several optical films such as an electromagnetic shielding film, a near-infrared ray blocking film, a color compensating film, an anti-reflection film, an external light blocking film, etc., which have respective functions, by a bonding agent or an adhesive. Among them, the external light blocking film blocks external light so as to improve a contrast ratio of a display apparatus.
However, since the external light blocking film absorbs external light even when the plasma display device is not driven, the screen of the plasma display device in an off state has a black color, which deteriorates the appearance thereof.
Furthermore, the latest plasma display device needs a further function of being capable of displaying pictures, information on weather or the like using only a small amount of electrical power when the plasma display panel is off, in addition to the basic display function when the plasma display panel is on.